Mobility handling in Ultra Dense Networks

ABSTRACT

User Equipment (UE) mobility in Ultra Dense Networks (UDNs) is based on communication signal layers, which could include respective data streams in an Orthogonal Frequency Division Multiplexing (OFDM) domain, a code domain using respective codebooks, and/or a spatial domain, for example. A UE uses candidate layer decoding parameters in applying layer-based decoding to communication signals that it received from network nodes. Layers could be allocated to UEs and transition between network nodes as UEs move between different network service areas. Layers could instead be allocated to network nodes. Layer-based decoding provides for UE mobility without requiring explicit handover processing every time a UE moves between different service areas.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/073,788, entitled “Mobility Handling In Ultra DenseNetworks”, filed on Mar. 18, 2016, which claims the benefit of U.S.Provisional Application Ser. No. 62/270,734, entitled “Mobility HandlingIn Ultra Dense Networks”, filed on Dec. 22, 2015, the entire contents ofboth of which are incorporated herein by reference.

FIELD

The present disclosure relates generally to Ultra Dense Networks (UDNs)and, in particular, to handling mobility in UDNs.

BACKGROUND

In UDNs, network nodes that provide wireless communication service touser equipment (UEs) are located closer to each other than in less dense“macro” networks. A UE may therefore transition between service areas ofdifferent network nodes when it is moved over a smaller distancerelative to the distance for transitions between service areas in lessdense networks. Service area transitions by UEs may also occur moreoften in UDNs.

Current Long Term Evolution (LTE) systems rely on handovers betweennetwork nodes to support UE mobility between service areas. It may bedesirable to avoid handover processing every time a UE transitionsbetween service areas, especially in networks such as UDNs in whichfrequent service area transitions may be expected.

SUMMARY

According to one aspect of the present disclosure, a method performed bya UE includes receiving a first plurality of communication signals froma first subset of network nodes when the UE is located in a firstservice area of a communication network, each communication signal ofthe first plurality of communication signals being associated with arespective one of a plurality of communication signal layers in thecommunication network; identifying first candidate communication signallayer decoding parameters, from a set of communication signal layerdecoding parameters that are available at the UE, for layer-baseddecoding of the first plurality of communication signals; applyinglayer-based decoding to the first plurality of communication signalsusing the first candidate communication signal layer decodingparameters; receiving a second plurality of communication signals from asecond subset of network nodes after the UE is moved to a second servicearea, each communication signal of the second plurality of communicationsignals being associated with a respective one of the plurality ofcommunication signal layers, the second subset of network nodesincluding at least one network node that is not in the first subset ofnetwork nodes; identifying second candidate communication signal layerdecoding parameters, from the set of communication signal layer decodingparameters that are available at the UE, for layer-based decoding of thesecond plurality of communication signals; applying layer-based decodingto the received second plurality of communication signals using thesecond candidate communication signal layer decoding parameters.

A UE according to another aspect of the present disclosure includes: areceiver to receive a first plurality of communication signals from afirst subset of network nodes when the UE is located in a first servicearea of a communication network, each communication signal of the firstplurality of communication signals being associated with a respectiveone of a plurality of communication signal layers in the communicationnetwork; and a signal decoder, coupled to the receiver, to identifyfirst candidate communication signal layer decoding parameters, from aset of communication signal layer decoding parameters that are availableat the UE, for layer-based decoding of the first plurality ofcommunication signals, and to apply layer-based decoding to the firstplurality of communication signals using the first candidatecommunication signal layer decoding parameters. The receiver is furtherconfigured to receive a second plurality of communication signals from asecond subset of network nodes after the UE is moved to a second servicearea of the communication network, each communication signal of thesecond plurality of communication signals being associated with arespective one of the plurality of communication signal layers, thesecond subset of network nodes including at least one network node thatis not in the first subset of network nodes. The signal decoder isfurther configured to identify second candidate communication signallayer decoding parameters, from the set of communication signal layerdecoding parameters that are available at the UE, for layer-baseddecoding of the second plurality of communication signals, and to applylayer-based decoding to the received second plurality of communicationsignals using the second candidate communication signal layer decodingparameters.

According to a further aspect of the present disclosure, a methodincludes: configuring a first subset of network nodes in a communicationnetwork to transmit first communication signals that are decodable by auser equipment (UE) using decoding parameters for communication signalsassociated with communication signal layers in the communicationnetwork, each of the first communication signals being associated with arespective one of the plurality of communication signal layers;configuring a second subset of the network nodes in the communicationnetwork to transmit second communication signals that are decodable bythe UE using the decoding parameters, the second subset of network nodesincluding at least one network node that is not in the first subset ofnetwork nodes, each of the second communication signals being associatedwith a respective one of the plurality of communication signal layers.

Another aspect of the present disclosure relates to an apparatus thatincludes a coordination controller to: configure a first subset ofnetwork nodes in the communication network to transmit firstcommunication signals that are decodable by the UE using the decodingparameters, each of the first communication signals being associatedwith a respective one of the plurality of communication signal layers;configure a second subset of the network nodes in the communicationnetwork to transmit second communication signals that are decodable bythe UE using the decoding parameters, the second subset of network nodescomprising at least one network node that is not in the first subset ofnetwork nodes, each of the second communication signals being associatedwith a respective one of the plurality of communication signal layers.The apparatus also includes a coordination interface, coupled to thecoordination controller, to communicate with the network nodes.

Other aspects and features of embodiments of the present disclosure willbecome apparent to those ordinarily skilled in the art upon review ofthe following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be described in greater detail withreference to the accompanying drawings.

FIG. 1 is a block diagram illustrating a communication network inaccordance with one embodiment.

FIG. 2 is a block diagram illustrating UE communication signal layerallocation and mobility.

FIG. 3 is a block diagram illustrating network node communication signallayer allocation and mobility.

FIG. 4 is a flow diagram of a method according to an embodiment.

FIG. 5 is a block diagram illustrating a UE according to an embodiment.

FIG. 6 is a flow diagram of a method according to another embodiment.

FIG. 7 is a block diagram illustrating a centralized processing systemaccording to an embodiment.

FIG. 8 is a block diagram illustrating a network node according to anembodiment.

DETAILED DESCRIPTION

For illustrative purposes, specific example embodiments will now beexplained in greater detail below in conjunction with the figures.

The embodiments set forth herein represent information sufficient topractice the claimed subject matter and illustrate the best way ofpracticing such subject matter. Upon reading the following descriptionin light of the accompanying figures, those of skill in the art willunderstand the concepts of the claimed subject matter and will recognizeapplications of these concepts not particularly addressed herein. Itshould be understood that these concepts and applications fall withinthe scope of the disclosure and the accompanying claims.

Moreover, it will be appreciated that any module, component, or devicedisclosed herein that executes instructions may include or otherwisehave access to a non-transitory computer/processor readable storagemedium or media for storage of information, such as computer/processorreadable instructions, data structures, program modules, and/or otherdata. A non-exhaustive list of examples of non-transitorycomputer/processor readable storage media includes magnetic cassettes,magnetic tape, magnetic disk storage or other magnetic storage devices,optical disks such as compact disc read-only memory (CD-ROM), digitalvideo discs or digital versatile discs (i.e. DVDs), Blu-ray Disc™, orother optical storage, volatile and non-volatile, removable andnon-removable media implemented in any method or technology,random-access memory (RAM), read-only memory (ROM), electricallyerasable programmable read-only memory (EEPROM), flash memory or othermemory technology. Any such non-transitory computer/processor storagemedia may be part of a device or accessible or connectable thereto.Computer/processor readable/executable instructions to implement anapplication or module described herein may be stored or otherwise heldby such non-transitory computer/processor readable storage media.

Turning now to the figures, some specific example embodiments will bedescribed.

FIG. 1 is a diagram illustrating a communication network in accordancewith one embodiment. The communication network 100 includes a corenetwork 102 and an access network 106.

The core network 102 may provide any of various services, such as callcontrol/switching and gateways to other networks. The core network 102includes network components such as routers, switches, and servers.

The access network 106 is a UDN, and is connected or coupled to the corenetwork 102. The network nodes 108 a, 108 b, 108 c, 108 d, 108 e, whichmay also be referred to as transmit points or TPs in UDN terminology,provide wireless communication service within respective wirelesscoverage areas 110 a, 110 b, 110 c, 110 d, 110 e. Each network node 108a-e may be implemented using a radio transceiver, one or more antennas,and associated processing circuitry, such as antenna radio frequency(RF) circuitry, analog-to-digital/digital-to-analog converters, etc.

UEs 104 a, 104 b, 104 c, 104 d wirelessly access the communicationnetwork 100 using the access network 106. Each UE 104 a-d includes aradio transceiver, one or more antennas, and associated processingcircuitry, such as antenna radio frequency (RF) circuitry,analog-to-digital/digital-to-analog converters, etc. The network nodes108-e and the UEs 104 a-d may include similar types of components tosupport communications with each other in the communication network 100,but the actual implementations may be different. For example, the UEs104 a-d are portable between locations, whereas the network nodes 108a-e are typically intended to be installed at a fixed location.

The network nodes 108 a-e are connected to a centralized processingsystem 120 in the access network 106, via respective communication links112 a, 112 b, 112 c, 112 d, 112 e. Each communication link 112 a-e is afibre communication link in one embodiment. Each network node 108 a-eincludes circuitry for transmitting data to the centralized processingsystem 120 and for receiving data from the centralized processing systemvia its respective communication link 112 a-e. Although shown as asingle centralized processing system in FIG. 1, the centralizedprocessing system 120 may be implemented by a network of one or moreprocessing and control servers. Alternatively, the centralizedprocessing system 120 may be implemented as a single server.

The network nodes 108 a-e may serve as a gateway between wireline andwireless portions of the access network 106, although this need not bethe case in embodiments in which the communication links 112 a-e arewireless links. Network nodes may be placed at fixed locations by anetwork provider, for example, in a strategic manner to provide acontinuous wireless coverage area. This is shown in FIG. 1 in thatwireless coverage areas 110 a-e overlap each other so that the UEs 104a-d may move throughout the wireless coverage areas and still be servedby the access network 106. At different locations in the access network106, different subsets of the network nodes 108 a-e provide wirelesscommunication service.

Some service areas in the access network 106 are serviced by a singlenetwork node, as in the case of the current locations of the UEs 104a-d. However, the wireless coverage areas 110 a-e also overlap with eachother. A UE, when located in a service area that has overlappingcoverage from multiple network nodes, is exposed to communicationsignals from those network nodes. A subset of network nodes providingcommunication service in a service area could therefore include one ormore network nodes.

In a UDN such as the access network 106, the network nodes 108 a-e arelocated closer to each other than in other types of communicationnetworks. A UE may therefore change service areas as a result of movingover a smaller distance than in a communication network in which thereare fewer network nodes, located farther away from each other, withlarger wireless coverage areas. In moving from left to right in FIG. 1,for example, the UE 104 a could transition through different serviceareas as follows:

-   -   from a service area that is serviced by the network node 108 a        to a service area that is serviced by the network nodes 108 a,        108 d (at a location within the overlapping region of the        wireless coverage areas 110 a, 110 d);    -   from the service area that is serviced by the network nodes 108        a, 108 d to a service area that is serviced by the network nodes        108 a, 108 d, 108 b (at a location within the overlapping        regions of the wireless coverage areas 110 a, 110 d, 110 b);    -   from the service area that is serviced by the network nodes 108        a, 108 d, 108 b to a service area that is serviced by the        network node 108 b;    -   and so on, through different service areas in which different        subsets including one or more of the network nodes 108 a-e        provide communication service.

In a UDN, these service area transitions could all occur for a UE thattravels only a few hundred metres, for example. Handover processing thatis used to support UE mobility in current LTE systems and othercommunication networks can represent a significant burden oncommunication and processing resources when service area transitionsoccur over such a short distance and are expected to be frequent.

The present disclosure proposes a communication signal “layer” approachto mobility in UDNs. Joint detection and decoding methods such asSuccessive Interference Cancellation (SIC), Message Passing Algorithm(MPA), or Maximum Likelihood Detection (MLD) allow a UE to jointlyreceive and decode communication signals that are associated withmultiple layers, which could be received from multiple network nodes.

Network node to UE associations may be applied dynamically, as disclosedherein. In an embodiment, multiple layers, which may originate frommultiple network nodes, are associated to a UE. As the UE moves, adifferent subset of network nodes takes responsibility for serving theUE. Service area transitions can be transparent to the UE, withtransparent layer to network node associations and/or transparent“active” network node subsets.

Communication signal layers, also referred to as simply “layers” herein,could include respective data streams in an Orthogonal FrequencyDivision Multiplexing (OFDM) domain, a code domain using respectivecodebooks, and/or a spatial domain, for example. In a code domain,communication signals associated with different layers are encoded usingdifferent codebooks. In one embodiment, incoming bits are mapped tosparse multi-dimensional complex codewords selected from predefinedcodebook sets in an approach that may also be known as Sparse CodeMultiple Access (SCMA). Spatial domain layers could be layers in aMultiple Input Multiple Output (MIMO) system, for example.

Layers could be allocated to UEs or to network nodes. Both of theseoptions are described in detail below. Although the detaileddescriptions below refer to code domain layers, other types of layersare also possible.

In a UE layer allocation approach, one or more layers are provisionedfor and allocated to a UE. This approach might be more suitable in alightly loaded network, for example, in which a sufficient number oflayers are available for allocation of at least one layer to each UE.FIG. 2 is a block diagram illustrating UE layer allocation and mobility.

In order to avoid congestion in the drawing, FIG. 2 shows only networknodes 208 a, 208 b, 208 c, 208 d, 208 e, 208 f of a UDN 200, without acentralized processing system or core network as shown in FIG. 1.Different locations of a UE are shown at 204A, 204B, 204C, and the A, B,C labels are intended to denote the different locations of the same UErather than different UEs. Movement of the UE is shown at 220, 222.Three layers are represented at 230A, 230B, 230C, 232A, 232B, 232C,234A, 234B, 234C, with the numbers 230, 232, 234 denoting the threedifferent layers and the A, B, C labels denoting the signals receivedwhen the UE is at each of the locations shown at 204A, 204B, 204C,respectively. The network node 208 f is not involved in the mobilityexample in FIG. 2, but is shown to illustrate that the communicationnetwork 200 could include additional network nodes that do not belong toany of the network node subsets that provide service to a UE as it movesbetween service areas within a communication network.

The UE is exposed to multiple communication signals at each location204A, 204B, 204C. At location 204A, for example, the UE receivescommunication signals that are respectively associated with the layers230A, 232A, 234A. The signals carried by the three layers 230A, 232A,234A are received by the UE from three different network nodes 208 a,208 b, 208 c in this example, but multiple layers could originate from asingle network node in other embodiments.

Interference caused by network nodes in serving other UEs is not alimiting factor in the communication system 200. The UE at location204A, for example, receives and applies layer-based decoding to thecommunication signals that are associated with the layers 230A, 232A,234A. For code domain layers, the UE receives a set of codebooks withcorresponding pilot patterns. The codebooks for different layers couldbe allocated and distributed to UEs by a centralized processing systemas shown at 120 in FIG. 1, for example. Multiple layers may share thesame pilot set and originate from the same physical/logical antenna portin some embodiments.

The UE estimates the channel or communication signal that is associatedwith each of the different layers, and attempts to jointly decode thedata associated to the UE. For code domain layers, the UE when locatedat 204A uses the layer codebooks to decode the received communicationsignals, and may discard the communication signals associated with anylayers that have not been allocated to it.

As the UE moves, a “potential” network node subset that includes thenetwork nodes that may provide service to the UE could change. Thepotential network node subset could be updated using one or more ofuplink (UL) reciprocity, a tracking channel, user feedback, locationservices, etc. Movement of the UE from the location 204A to the location204B, as represented at 220, could be detected by a centralizedprocessing system shown at 120 in FIG. 1, for example. The potentialnetwork node subset now includes the network nodes 208 b, 208 c, 208 dthat provide communication service in the service area in which the UEis now located. This potential network node subset is determined basedon the current location of the UE at 204B. Again, this could be handledby a centralized processing system, which could also advise the networknode 208 d that it is part of the potential network node subset for theUE. The network node 208 a could similarly be advised, by a centralizedprocessing system or other component in the communication network 200,that it is no longer part of the subset that is providing service to theUE.

When the UE is at location 204B, it is the network node 208 d that isresponsible for the layer 230. 230A and 230B in FIG. 2 represent thesame layer. This layer could therefore be considered to have beentransferred from the network node 208 a to the network node 208 d,following the UE as it moves. The UE may not be aware of the currentnetwork node-layer association. From the perspective of the UE,communication signals associated with the same layers are received atthe locations 204A and 204B, and the UE need not necessarily be awarethat one of the layers has moved from the network node 208 a to thenetwork node 208 d. As far as the UE is concerned, it is decodingcommunication signals associated with the same layers, using the samecodebooks in a code domain layer implementation for example, whether itis at the location 204A or the location 204B. This type of layertransition between different network nodes could be transparent to theUE, although it could instead be acknowledged, by the UE and/or networknode(s), in other embodiments.

The same consistency of communications and layers also applies formovement of the UE from the location 204B to the location 204C,represented at 222. In this case, the layer 234 is moved from thenetwork node 208 b to the network node 208 e, as shown at 234C.

Such UE layer allocation and transitioning of layers between differentnetwork nodes may be used to support mobility without requiring explicithandover processing every time the potential network node subset changesas the UE moves between service areas.

Even with UE layer allocation, codebooks could be updated. UE codebookscould be periodically updated and distributed, by a centralizedprocessing system as shown at 120 in FIG. 1 for example. Codebooks andcodebook assignments could therefore be considered to be dynamic orsemi-static, depending on how often codebook updates are made. However,such codebook updating is not necessarily performed as part of the layertransition process outlined herein. A UE could use the same codebook(s)for its allocated layer(s), regardless of the particular network nodesin the current active or potential network node subset, if the UE movesbetween service areas before a codebook update occurs and the layersremain the same after the UE is moved into a different service area.

The layers need not necessarily remain the same as a UE is moved betweendifferent service areas. For example, a layer might not have beentransferred to a different network node when the UE moves into adifferent service area, and that layer would then be absent from theactive set of layers for a period of time. A layer could instead beremoved entirely or re-allocated to a different UE, and not moved to adifferent network node as the UE moves between service areas. A layercould be removed or re-allocated, for example, in embodiments in which adifferent layer is allocated to the UE, or multiple layers are allocatedto the UE and one or more layers remain allocated to the UE after alayer is removed.

Other communication characteristics could similarly be dynamic orsemi-static. For example, characteristics such as Forward ErrorCorrection (FEC) coding rate and/or the actual number of layersallocated to a UE could be updated frequently, such as at each downlink(DL) grant.

A UE could perform blind detection to determine the layers that areactive at its current location. Blind detection relates to identifyingresources based on properties of the received signal, without a prioriknowledge such as signaling from the transmitter to indicate whichresources are being used. In a blind detection implementation, the UEblindly detects the active layer set, by determining the layers forwhich it is able to decode communication signals. A UE could instead beinformed of the active layers by one or more network nodes, for exampleas part of a grant of wireless resources. Either of these approachescould provide for distributed scheduling, with each network nodedeciding whether to serve the UE.

Other options for a UE layer allocation system include vertical orhorizontal coding. In a synchronous network, for example, verticalcoding could utilize the same FEC block for all layers and involve somedata sharing.

Some embodiments may support layer “lending”. For example, a centralizedprocessing system could make a decision to use a UE's codebook from oneor multiple network nodes to serve other UEs. In this case, a UE couldjointly decode communication signals associated with all the layers fromall network nodes, but keep only its own data and discard data intendedfor other UEs.

FIG. 2 and the description above relate to UE layer allocation. Networknode layer allocation is also possible. A network node layer allocationsolution might be more suited for scenarios in which the network load ishigh and/or the number of UEs is greater than the number of availablelayers, for example. FIG. 3 is a block diagram illustrating network nodelayer allocation and mobility.

As in FIG. 2, FIG. 3 shows only network nodes 308 a, 308 b, 308 c, 308d, 308 e, 308 f of a UDN 300, different locations of a UE are shown at304A, 304B, 304C, and movement of the UE is shown at 320, 322. Layers330, 332A, 332B, 332C, 334A, 334B, 336A, 336B, 338 in FIG. 3, however,are allocated to the network nodes 308 a, 308 b, 308 c, 308 d, 308 einstead of to the UE.

In FIG. 3, each network node 308 a, 308 b, 308 c, 308 d, 308 e isassigned one or more layers. One or more layers could also be allocatedto the network node 308 f, but are not shown in FIG. 3 because thenetwork node 308 f is not involved in providing service to the UE inthis example.

In a code domain layer system, a list of the possible codebooks andpilots, for layers that are allocated to network nodes in the vicinityof the UE, is distributed to the UE. Such a list of the possiblecodebooks and pilots is an example of candidate decoding parameters thatthe UE is to use in applying layer-based decoding to receivedcommunication signals. A list of candidate decoding parameters couldinclude information identifying decoding parameters not only for layersthat are active within a service area in which the UE is currentlylocated, but also for layers that may be active in a different servicearea, such as a service area that is adjacent to the current servicearea. In this example, if the UE moves from the service area to theadjacent service area, then the UE may use the same candidate decodingparameters to attempt to decode received communication signals.

Layers for the same network node could share the same pilot pattern. TheFEC code rate and possibly other related information could also becommunicated to the UE. This information could be explicitly known tothe UE, either through broadcast or unicast signaling or by beingstandardized within the network 300 so it is known a priori to the UE.

At each location 304A, 304B, 304C, the UE is exposed to multiplecommunication signals. Each communication signal is associated with adifferent layer, and is received from a different network node in FIG.3. For example, at location 304A the UE receives communication signalsthat are respectively associated with the layers 330, 332A, 334A, fromthe network nodes 308 a, 308 b, 308 c.

The UE applies layer-based decoding to the received communicationssignals, using the candidate codebooks. The UE could report, to acentralized processing system as shown at 120 in FIG. 1 for example, alist of codebooks that were successful in decoding the receivedcommunication signals. This could involve a direct or indirectmeasurement channel. A UE could use previous transmit time interval(TTI) information to determine the layers for which communicationsignals are decodable, and use a measurement channel to send a list ofdecodable layers to a centralized processing system, for example.Information regarding the layers for which communication signals aredecodable, or another type of indication of which candidate layerdecoding parameters were used to decode received communication signals,could be used to determine the current location of the UE, because thecommunication signals that are decodable are associated with the layersthat are allocated to the network nodes 308 a, 308 b, 308 c when the UEis at location 304A. More generally, the location of the UE could bedetermined based on the layer decoding parameters, such as codebooks,that it is able to use to successfully decode communication signals, andthe network nodes to which the layers associated with the decodablesignals are allocated. The UE is able to successfully decodecommunication signals using different codebooks, for example, dependingon its location.

After the UE moves to location 304B, as represented at 320, the UEreceives communication signals from the network nodes 308 b, 308 c, 308d and applies layer-based decoding to the received signals. The UE isnow able to use the codebooks for the layers that are allocated to thosenetwork nodes to successfully decode communication signals. Thecodebooks and the layers that are active at the location 304B includethe layers 332B, 334B, 336A. Two of these layers 332B, 334B areassociated with signals that are received at location 204A, but in thisexample there is one different layer 336A. There is no layer transitionbetween different network nodes in FIG. 2. The UE might not be aware ofthe current network node-layer association at the current location ofthe UE. The UE when at the location 304B could still be attempting todecode the received communication signals using the same set ofcandidate codebooks that it used when at the location 304A. At thelocation 304B, a candidate codebook that could not be used tosuccessfully decode any communication signals that were received at thelocation 304A now corresponds to a received signal and can decode thereceived communication signal.

In another embodiment, information identifying a different set ofcandidate decoding parameters, codebooks in this example, is transmittedto the UE when a network node or centralized processing systemdetermines that the UE has moved between service areas. However, as inthe UE layer allocation mobility example in FIG. 2, there need not beany explicit handover processing in FIG. 3 when the active subset ofnetwork nodes changes from 308 a, 308 b, 308 c at the location 304A, to308 b, 308 c, 308 d at the location 304B. The UE may receive informationidentifying new candidate decoding parameters when it moves betweenservice areas, but still need not be aware that the new candidatedecoding parameters are for layers that originate from a differentsubset of network nodes, which includes at least one different networknode, in a different service area.

Further movement of the UE from the location 304B to the location 304C,represented at 322, similarly changes the active subset of network nodesto 308 c, 308 d, 308 e. Two of the layers 332C, 336B are the same as atthe location 304B, but the codebook for layer 338 is now able to decodecommunication signals that are received by the UE at the location 304C.

Layer to network node allocation in a network node layer allocationimplementation could be semi-static or static, depending on the numberof network nodes and the number of codebooks that are available forallocation, for example. Layers could also or instead be initiallyallocated to network nodes or moved from one network node to another,for example for load balancing or energy saving. New or updated codebookallocations are distributed to network nodes by a centralized processingsystem as shown at 120 in FIG. 1 in one embodiment. New or updatedcodebook and pilot signal lists could similarly be distributed to UEs.

Scheduling of a UE in a network node layer allocation system could behandled by each network node (distributed scheduling) or in acentralized manner by a centralized processing system as shown at 120 inFIG. 1. The decisions of a scheduler could be sent as part of a grant ofwireless resources, or blindly detected by the UE based on the layersfor which it is able to decode communication signals.

Layer coordination could be dynamically optimized by network nodescoordinating with each other or under control or direction of acentralized processing system. Such dynamically optimized layercoordination may, however, place higher requirements on backhaul andsynchronization. Other options for layer coordination includesemi-statically optimized layer coordination and long term coordinationand settings, which could be implemented with more relaxed backhaul andsynchronization requirements. Hybrid coordination, to accommodatedifferent levels of cooperation between network nodes, is a furtheroption.

FIG. 4 is a flow diagram of a method according to an embodiment. Themethod 400 is illustrative of a method performed by a UE.

At 402, the UE receives communication signals from a subset of networknodes, as described above with reference to FIGS. 2 and 3. Each of thereceived communication signals is associated with a respective one ofmultiple layers.

Candidate layer decoding parameters are identified at 404. Thisidentification of candidate decoding parameters could involve accessinga list of candidate codebooks in a memory, for example. Such a list, ormore generally information identifying candidate decoding parameters,could be generated by a network node or a centralized processing systembased on the current location of the UE, and distributed to the UE. Thecandidate decoding parameters could include all decoding parameters thatare available at the UE, or a subset of those decoding parameters.Information that identifies the candidate decoding parameters that theUE is to use in layer-based decoding of received communication signalsneed not include the decoding parameters. The decoding parameters couldbe distributed to the UE separately, and the decoding parameters arethen available at the UE for use in layer-based decoding.

The candidate decoding parameters could include a set of codebooks forall layers in a network or at least codebooks for layers that may beactive in one or more service areas of the network. The layers that maybe active in a service area could include layers that are already activein the case of network node layer allocation, or layers that are not yetactive but may subsequently become active after the UE moves to adifferent service area in the case of UE layer allocation and layertransition between network nodes.

Layer-based decoding is applied to the received communication signals at406. The layer-based decoding uses the candidate layer decodingparameters identified at 404. The UE attempts to decode the receivedcommunication signals using the candidate decoding parameters.

Consider the example shown in FIG. 2, in the context of code domainlayers. At the location 204A, the UE applies layer-based decoding usingthe codebooks for the three layers 230A, 232A, 234A that it receives.With layer transition between network nodes as shown in FIG. 2, the samecodebooks are also used at the location 204B, to apply layer-baseddecoding to additional communication signals that are received by the UEat that location. Thus, the codebooks are an example of layer decodingparameters for the layers with which the current received communicationsignals at location 204A are associated, regardless of the particularnetwork nodes from which the layers originate.

Similarly, in the network node layer allocation example shown in FIG. 3,the UE applies layer-based decoding using the codebooks for the threelayers 330, 332A, 334A associated with the communication signals that itreceives at the location 304A. As noted above, not all layers may bedecodable at this location of the UE. However, the UE may still attemptto decode (that is, apply layer-based decoding) using all of thecodebooks in its current candidate codebook list, and determine thelayers for which communication signals are decodable. Some of thecandidate codebooks might work, and others might not. The codebook forthe layer 336A cannot be used to successfully decode a communicationsignal when the UE is at the location 304A, but will work when the UEmoves to the location 304B. Thus, the candidate codebooks in thisexample represent one form of decoding parameters for the layers withwhich the current received communication signals at location 304A areassociated, and also for layers outside the current service area, afterthe UE moves to the location 304B.

The method 400 may be repeated as new communication signals arereceived. A UE could receive new communication signals while it remainsin the same service area and attempt to decode those signals asdescribed above. The UE could instead transition to a different servicearea as shown at 408, and receive communication signals at 402 from adifferent subset of network nodes. The UE may identify some or all ofthe same candidate layer decoding parameters at 404 as in the previousservice area, and use those candidate decoding parameters at 406 toattempt to decode the new received communication signals. Theidentification of candidate layer decoding parameters could be based oninformation that is received by the UE, from a centralized processingsystem as shown at 120 in FIG. 1, for example. The received informationcould include information identifying first candidate communicationsignal layer decoding parameters to be used by the UE in one servicearea, and information identifying second candidate communication signallayer decoding parameters to be used by the UE after it is moved to adifferent service area.

Candidate decoding parameters may, but need not necessarily, change whena UE moves between service areas. In the UE layer allocation mode, forexample, the communication signal layers allocated to the UE could bethe same in different service areas, and therefore the same candidatedecoding parameters could be identified by the UE at 404 and used indifferent service areas. In the network node layer allocation mode, theUE could be provided with information identifying decoding parametersfor layers that might be active in its current service area and layersthat might be active in an adjacent service area. In this scenario, theUE could use the same candidate decoding parameters when it is locatedin the current service area and after it moves to the adjacent servicearea.

In the UE layer allocation case, the layer decoding parameters are fordecoding communication signals associated with a layer that is allocatedto the UE. These parameters are independent of which particular one ofthe network nodes transmits the communication signals. For the networknode layer allocation case, the decoding parameters are for decodingcommunication signals associated with layers that are allocated to thenetwork nodes.

The example method 400 is illustrative of one embodiment. Otherembodiments could include different or additional operations. Examplesof additional operations that may be performed, and/or various ways toperform the illustrated operations, may be or become apparent.

For example, different layers from the same network node or differentnetwork nodes could be decoded at 404 using any of a variety of decodingmethods, such as SIC, MPA, joint detection, MLD and MIMO (linear ornon-linear) decoders, or a combination of decoding methods.

In some embodiments, UE location is tracked based at least in part onthe layer(s) for which communication signals are successfully decoded.An example of an additional operation that could be performed in such anembodiment is transmitting, to a network node, an indication of thecandidate decoding parameters that were used to successfully decodecommunication signals. This operation could be performed after 406 inFIG. 4, for instance. In a mobility scenario, a UE could transmit to anetwork node of a first subset of network nodes an indication of whichof first candidate decoding parameters were used to decode a firstplurality of received communication signals, and/or transmit to anetwork node of a second subset of network nodes an indication of whichof second candidate layer decoding parameters were used to decode asecond plurality of communication signals received after a service areatransition.

For example, the UE could detect a change in the set of layer decodingparameters that were used to successfully decode received communicationsignals, and, in response to detecting the change, transmit anindication of which layer decoding parameters were used to decodecommunication signals. Transmission of such an indication could also orinstead be request-based, with the UE transmitting an indication inresponse to a request from a centralized processing system or networknode. Other options, including periodic or scheduled transmission times,are also possible.

The description above refers generally to layers and to communicationsignals that are associated with such layers. There could be multipletiers of layers. The decoding method could separate different datalayers, with a UE first successfully decoding communication signalsassociated with one layer before proceeding to the next. A tieredstructure could instead involve multiple layers in an arrangement suchthat communication signals associated with layers at one tier would bedecoded before attempting to decode at a higher tier. For example, afirst layer could have a relatively low modulation and coding scheme(MCS) and a second layer could have a relatively high MCS, such that thefirst layer can be decoded without knowledge of the second layer, and itis advantageous to decode the first layer prior to decoding the secondlayer. In both cases, there may be multiple tiers of layers, andlayer-based decoding is first applied to decode one or morecommunication signals associated with layers of a first tier beforeapplying layer-based decoding to communication signals of a second tier.A special case of a tiered structure includes only one layer per tier.

FIG. 5 is a block diagram illustrating a UE 500 that may perform theabove methods according to an embodiment. The example UE 500 includes anantenna 502, a receiver 504 operatively coupled to the antenna, and adecoder 506 operatively coupled to the receiver. Although embodimentsdisclosed herein relate primarily to receiving and decodingcommunication signals, a UE may include components such as a transmitter508 and an encoder 510 operatively coupled to the transmitter. Thetransmitter 508 is also operatively coupled to the antenna 502, and tothe decoder 506 in the example shown.

Although a single antenna 502 is shown in FIG. 5, a UE could includemultiple antennas. Separate receive and transmit antennas or sets ofmultiple antennas could be provided at 502, or the same antenna or setof multiple antennas could be used for both receiving and transmittingcommunication signals. The antenna 502 could include one or moreantennas of any of various types. The type(s) of antenna(s) provided at502 could be implementation-specific.

In general, hardware, firmware, components which execute software, orsome combination thereof might be used in implementing the receiver 504,the decoder 506, the transmitter 508, and the encoder 510. Electronicdevices that might be suitable for implementing any or all of thesecomponents include, among others, microprocessors, microcontrollers,Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), Application Specific Integrated Circuits (ASICs), and othertypes of “intelligent” integrated circuits.

Software and/or information such as codebooks that may be used inoperation of the UE 500 could be stored in one or more physical memorydevices. Solid-state memory devices and/or memory devices with movableor even removable storage media could be implemented. Examples of memorydevices are provided above. Memory devices could be internal to one ormore of the components shown in FIG. 5, and therefore have not beenshown separately in the drawing. External memory devices operativelycoupled to the illustrated components, or to one or more processors thatimplement those components, are also possible.

The receiver 504 could perform such operations as frequencydown-conversion and demodulation, and the transmitter 508 could performinverse operations, including frequency up-conversion and modulation.The receiver 504 and the transmitter 508 could perform other operationsinstead of or in addition to these example operations, depending on thespecific implementation and the types of communication functions andprotocols to be supported. The decoder 506 applies layer-based decodingto received communication signals as described herein, and the encoder510 applies encoding in accordance with the layer or layers on which theUE transmits to network nodes.

The receiver 504 is operative to receive communication signals from oneor more network nodes that provide communication service in a servicearea of a communication network. Each communication signal is associatedwith a respective layer. The decoder 506 is operative to applylayer-based decoding to the received communication signals usingcandidate layer decoding parameters, as described above with referenceto FIG. 4, for example. The receiver 504 and the decoder 506 could beconfigurable, by executing software in a processor-based embodiment forexample, to perform these and other operations. Examples of otheroperations that the receiver 504 and/or the decoder 506 could beconfigured to perform are described above. The decoder 506, for example,could be further configured to transmit, through the transmitter 508which enables the UE 500 to transmit signals to network nodes, anindication as to which candidate decoding parameters were used to decodereceived communication signals. Such an indication could be used bynetwork nodes, and/or a centralized processing system, to track locationof the UE 500.

FIG. 6 is a flow diagram of a method according to another embodiment.The method 600 is illustrative of a method performed by networkequipment. The method 600 could be centralized, and performed in thecommunication network at a centralized processing system as shown at 120in FIG. 1, for example. The method 600 could instead be performed in adistributed manner, at multiple network nodes, with the multiple networknodes communicating with each other to determine layer allocations andtheir own configurations.

Layer allocations are coordinated at 602, by a centralized processingsystem as shown at 120 in FIG. 1 for example, or by network nodes. Thecoordination at 602 involves determining how layers should be allocated.Layers could be allocated to UEs or to network nodes as described above.Factors such as any one or more of: the number of layers available forallocation, the number of UEs, the number of network nodes in thenetwork, load balancing, and energy saving could be taken into accountin coordinating layer allocations. After a layer allocation has beendetermined, layers are allocated, to UEs or to network nodes, at 604.

Decoding parameters for decoding communication signals that areassociated with different layers are distributed to UEs at 606. At 608,a first subset of network nodes (such as the network nodes 208 a, 208 b,208 c in FIG. 2 or 308 a, 308 b, 308 c in FIG. 3) are configured totransmit first communication signals that are decodable by the UE usingthe decoding parameters. A second subset of network nodes (such as thenetwork nodes 208 b, 208 c, 208 d in FIG. 2 or 308 b, 308 c, 308 d inFIG. 3) are also configured to transmit second communication signalsthat are decodable by the UE using the decoding parameters. A networknode could be configured to transmit communication signals that areassociated with multiple layers.

In a network node layer allocation embodiment, for example, layers areallocated to network nodes. Configuration of the network nodes of thefirst subset and the second subset could be performed at the same timeat 604.

However, the network nodes of the first and second subsets need notnecessarily be configured at the same time. In embodiments in whichlayers are allocated to UEs, a location of the UE could be tracked andat least a network node in the second subset that will take overresponsibility for a particular layer from a network node in the firstsubset (after the UE moves into the second service area) might not beconfigured until the UE has moved into or is at least close to enteringthe second service area. With reference to FIG. 2, for example, thenetwork node 208 a could be configured to transmit communication signalsassociated with the layer 230A when the UE is at the location 204A. Thenetwork node 208 d, which takes over responsibility for this layer fromnetwork node 208 a when the UE moves to the location 204B, might beconfigured to transmit communication signals associated with the layer230B, in response to detecting movement of the UE from the first servicearea at the location 204A to the second service area at the location204B.

FIG. 6 represents an illustrative embodiment. Other embodiments couldinclude additional or different operations, performed in an order thatis similar to or different from the order shown in FIG. 6.

For example, a method could involve scheduling transmission ofcommunication signals by the network nodes. Such scheduling could beperformed at a centralized processing system in the communicationnetwork, or in a distributed manner at each of the network nodes.

A method could also or instead include tracking a location of the UE inthe communication network, determining based on a current location ofthe UE candidate decoding parameters that are to be used by the UE indecoding communication signals received by the UE, and transmitting tothe UE information identifying the candidate decoding parameters.Location tracking could involve receiving from the UE an indication asto which decoding parameters were used to decode communication signalsthat are received by the UE, and tracking a location of the UE in thecommunication network based on the indication. In some embodiments,other information is also or instead taken into account for locationtracking.

FIG. 7 is a block diagram illustrating a centralized processing systemaccording to an embodiment. The example centralized processing system700 includes a decoding parameter distributor 702, a coordinationcontroller 704, and a scheduler 708, all operatively coupled to acoordination interface 706. Hardware, firmware, components which executesoftware, or some combination thereof might be used in implementing atleast the decoding parameter distributor 702, the coordinationcontroller 704, and the scheduler 708. The coordination interface 706includes one or more physical ports or connectors to a communicationmedium through which the centralized processing system 700 communicateswith network nodes. The coordination interface 706 also includescommunication circuitry, which could be hardware-, software-, and/orfirmware-based, to support communications with the base stations. Theform of the coordination interface 706 is dependent upon thecommunication medium or media and/or protocol(s) to be supported betweenthe centralized processing system 700 and the network nodes.

The decoding parameter distributor 702 is operative to distributedecoding parameters to a UE, as described above with reference to FIG.6, through the coordination interface 706 and one or more network nodes.Distribution to UEs from the centralized processing system 700 couldtherefore be indirect, through the coordination interface 706 andnetwork nodes with which the centralized processing system and the UEscommunicate.

The coordination controller 704 is operative to configure a first subsetof network nodes and a second subset of network nodes in the mannerdescribed with reference to 604 in FIG. 6. The coordination controller704 could be further configured to allocate a layer to a UE and toconfigure a network node of the first subset to transmit a communicationsignal associated with the layer, in a UE layer allocation model. Thecoordination controller 704 could also be configured to detect movementof the UE from the first service area to the second service area, and toconfigure a network node of the second subset to transmit acommunication signal associated with the layer, thereby providing layertransitions between network nodes for UE mobility.

To implement network node layer allocation, the coordination controller704 could be configured to allocate layers to the network nodes, and toconfigure network nodes of the first subset and the second subset totransmit communication signals respectively associated with the layersthat are allocated to the network nodes.

Scheduling could be centralized as noted above, and the scheduler 708 isconfigured to schedule transmission of communication signals by thenetwork nodes. A scheduler might not be provided at a centralizedprocessing system in distributed scheduling embodiments.

Some aspects of coordination between network nodes and/or schedulingcould be implemented at the network nodes. FIG. 8 is a block diagramillustrating a network node according to an embodiment. The examplenetwork node includes a coordination controller 804, an encoder 806, atransmitter 808, one or more antennas at 810, a coordination interface812, a scheduler 813, a decoder 814, and a receiver 816, which areoperatively coupled together as shown.

Hardware, firmware, components which execute software, or somecombination thereof might be used in implementing at least thecoordination controller 804, the encoder 806, the transmitter 808, thescheduler 813, the decoder 814, and the receiver 816. The antenna shownat 810 could include separate receive and transmit antennas or sets ofantennas, or the same antenna or sets of antennas could be used for bothreceiving and transmitting communication signals. One or more antennasof any of various types could be provided at 810, and the antennatype(s) could be implementation-specific. The antenna(s) at 810 arecompatible with the UE antenna(s) 502 (FIG. 5), to enable communicationsbetween the network node 800 and UEs. The coordination interface 812 issimilarly compatible with the coordination interface 706 and may beimplemented in a similar manner, in embodiments that include acentralized processing system. Network nodes may also or insteadcommunicate with each other, through compatible coordination interfaces812 at each network node. Communication circuitry in the coordinationinterface 812 could be hardware-, software-, and/or firmware-based, tosupport communications with a centralized processing system and/or othernetwork nodes. The form of the coordination interface 812 is dependentupon the communication medium or media and/or protocol(s) to besupported.

The coordination controller 804 could cooperate with the coordinationcontroller 704 (FIG. 7) at a centralized processing system indistributing decoding parameters to UEs and/or in configuring thenetwork node 800. For example, the coordination controller 804 couldreceive decoding parameters from the coordination controller 704,through the coordination interfaces 706, 812, and control thetransmitter 808 to transmit those parameters to a UE. The coordinationcontroller 804 could also or instead receive layer information, such asa codebook to be used by the network node 800, from the coordinationcontroller 704, and configure the encoder 806 and/or the transmitter 808so that the network node 800 transmits communication signals associatedwith one or more particular layers. Coordination between network nodescould instead be distributed, with the coordination controllers 804 atthe network nodes being configured to communicate with each other tocoordinate allocation and distribution of decoding parameters and/orconfiguration of the network nodes.

Although the network node 800 also includes a scheduler 813, ultimatecontrol of network node scheduling could be centralized. The scheduler813 could be controlled by the scheduler 708 (FIG. 7) of a centralizedprocessing system, for example. A network node would still beresponsible for scheduling traffic at the network node, but thescheduling is centrally controlled. The scheduler 813 at each networknode could instead be responsible for its own scheduling, in adistributed scheduling system.

What has been described is merely illustrative of the application ofprinciples of embodiments of the present disclosure. Other arrangementsand methods can be implemented by those skilled in the art.

The contents of the drawings are intended solely for illustrativepurposes, and the present invention is in no way limited to theparticular example embodiments explicitly shown in the drawings anddescribed herein. For example, FIGS. 1 to 3 are a block diagrams ofcommunication networks in which embodiments may be implemented. Otherembodiments could be implemented in communication networks that includemore network nodes than shown, or that have different topologies thanthe example shown. Similarly, the example methods in FIGS. 4 and 6, theexample UE in FIG. 5, the example centralized processing system in FIG.7, and the example network node in FIG. 8 are also intended solely forillustrative purposes.

Other implementation details could also vary between differentembodiments. Layer-based coordination in a UDN as disclosed herein, forexample, could coexist with other transmission schemes. OFDM or codedivision layers need not only be targeted to mobile UEs, but could beallocated to “cell center” low mobility UEs.

Layer-based coordination as disclosed herein could involve transfer ofvarious types of information between a central processing system,network nodes, and/or UEs. Any of various signaling approaches could beimplemented.

Considering UE layer assignment, signaling at a higher level in aprotocol stack could be used for initial signature/codebook allocationand/or updates in semi-static or dynamic systems. MCS signaling couldsimilarly support dynamic or semi-static MCS allocation or assignment.Grant signaling, in embodiments in which scheduling is not blind, coulduse a Physical Downlink Control CHannel (PDCCH) in LTE-based systems,for example. Feedback for reporting signal strength and/or ChannelQuality Indicator (CQI) could be implemented on a per link and/or TimeDivision Duplex (TDD) basis. Acknowledgement/negative acknowledgement(ACK/NAK) signaling could use a collective ACK or individual ACKs.

For network node codebook allocation, higher-level signaling could beused to distribute a list of possible codebooks and/or otherlayer-related information. A measurement channel for UE reporting couldbe direct, indirect, or hybrid. As noted above for UE layer allocation,scheduling in a network node layer allocation system could be blindlydetected or included in grant signaling, using a PDCCH for grantsignaling for example. ACK/NAK signaling could be ACK-based for blind orACK/NAK for PDCCH based grant signaling. Optional feedback signaling fora UE to report a list of decodeable layers, for example, could be TDDbased or hybrid. Although horizontal and vertical coding are options ina UE layer allocation system, vertical coding is preferred for a networknode layer allocation system.

These are illustrative of implementation details could be implemented inconjunction with layer-based multi-point transmission as disclosedherein.

The present disclosure focuses primarily on UE reception and decoding ofcommunication signals. It should be appreciated, however, that UEs mayalso transmit communication signals to network nodes. Communicationsignals transmitted by a UE are similarly associated with the layer(s)that are allocated to the UE or to the network node(s) to which the UEis transmitting. For example, the receiver 816 (FIG. 8) at a networknode could receive signals from a UE. A signal received from a UE couldinclude an indication as to which decoding parameters were used todecode communication signals that were received by the UE. A receivedindication could be provided to the coordination controller 804 at thenetwork node, to the coordination controller at one or more othernetwork nodes through the coordination interface 812, and/or to thecoordination controller 704 (FIG. 7) at a centralized processing systemthrough the coordination interfaces 812, 706. Any or all of thesecoordination controllers may then track a location of the UE in thecommunication network based on the indications.

Different layers may involve different levels of cooperation betweennetwork nodes. For example, suppose there are three network nodes toserve a UE in a UE layer allocation embodiment, with only two of thenetwork nodes connected through relatively fast backhaul connections andthe third network node being connected through a slower backhaulconnection. The network nodes with the faster backhaul connections coulduse a joint scheduler which dynamically assigns the layers of the UE tothe two network nodes. However, any backhaul exchange between the twonetwork nodes and the third network node would be slower, and static orsemi-static cooperation and/or layer allocation would be more suitablefor the third network node.

In embodiments disclosed herein, service could be considered to bemoving with a UE. Cooperation between network nodes may be simplifiedand may provide seamless service to a UE as the UE moves betweendifferent coverage areas of a network.

Embodiments also provide for multi-layer cooperation. Multi-sitediversity may improve channel stability and make communication channelsless susceptible to channel aging caused by mobility.

In addition, although described primarily in the context of methods andsystems, other implementations are also contemplated, as instructionsstored on a non-transitory processor-readable medium, for example.

We claim:
 1. A method performed by a user equipment (UE), the methodcomprising: receiving a physical downlink control channel (PDCCH) basedon spatial domain layer decoding parameters, the PDCCH identifyingspatial domain layers in a communication network; receiving a pluralityof communication signals from a subset of network nodes in thecommunication network, each communication signal of the plurality ofcommunication signals being associated with a respective one of thespatial domain layers in the communication network; decoding theplurality of communication signals using the spatial domain layerdecoding parameters; transmitting, to the subset of network nodes,acknowledgement/negative acknowledgement (ACK/NAK) signaling comprising,for each respective spatial domain layer, an indication of which of thespatial domain layer decoding parameters were used to decode thecommunication signal associated with the respective spatial domainlayer.
 2. The method of claim 1, further comprising receivinghigher-level signaling comprising spatial domain layer decodingparameters for spatial domain layers that are allocated to the subset ofnetwork nodes in the communication network.
 3. The method of claim 1,wherein the decoding comprises decoding the plurality of communicationsignals using a Multiple Input Multiple Output (MIMO) decoder.
 4. Anon-transitory processor-readable medium storing instructions which,when executed by one or more processors of a user equipment (UE), causethe UE to: receive a physical downlink control channel (PDCCH) based onspatial domain layer decoding parameters, the PDCCH identifying spatialdomain layers in a communication network; receive a plurality ofcommunication signals from a subset of network nodes in thecommunication network, each communication signal of the plurality ofcommunication signals being associated with a respective one of thespatial domain layers in the communication network; decode the pluralityof communication signals using the spatial domain layer decodingparameters; transmit, to the subset of network nodes,acknowledgement/negative acknowledgement (ACK/NAK) signaling comprising,for each respective spatial domain layer, an indication of which of thespatial domain layer decoding parameters were used to decode thecommunication signal associated with the respective spatial domainlayer.
 5. The non-transitory processor-readable medium of claim 4,comprising instructions, which when executed by the one or moreprocessors of the UE, cause the UE to receive higher-level signalingcomprising spatial domain layer decoding parameters for spatial domainlayers that are allocated to the subset of network nodes in thecommunication network.
 6. The non-transitory processor-readable mediumof claim 4, wherein the plurality of communication signals are decodedusing a Multiple Input Multiple Output (MIMO) decoder.
 7. A userequipment (UE) comprising: a processor; a memory storing instructionswhich, when executed by the processor causes the UE to: receive aphysical downlink control channel (PDCCH) based on spatial domain layerdecoding parameters, the PDCCH identifying spatial domain layers in acommunication network; receive a plurality of communication signals froma subset of network nodes in the communication network, eachcommunication signal of the plurality of communication signals beingassociated with a respective one of the spatial domain layers in thecommunication network; decode the plurality of communication signalsusing the spatial domain layer decoding parameters; transmit, to thesubset of network nodes, acknowledgement/negative acknowledgement(ACK/NAK) signaling comprising, for each respective spatial domainlayer, an indication of which of the spatial domain layer decoderparameters were used to decode the communication signal associated withthe respective spatial domain layer.
 8. The UE of claim 7, wherein thememory stores instructions which, when executed by the processor, causesthe UE to receive higher-level signal comprising spatial domain layerdecoding parameters for spatial domain layers that are allocated to thesubset of network nodes in the communication network.
 9. The UE of claim7, wherein the plurality of communication signals are decoded using aMultiple Input Multiple Output (MIMO) decoder.